Swimmers that practice in pools generally have a need to keep track of the number of laps that they swim in a pool. It is also desirable to keep track of the time it takes to swim each lap as well as a series of laps.
For short swims it is relatively easy for the swimmer to keep track of the number of laps she has swum herself. However, on longer training swims, where a swimmer may swim tens or hundreds of laps, it is difficult for the swimmer to keep track of his count. When training with a coach, the coach may keep track of the laps and the time elapsed (or even individual lap times), however most swimmers do not have the luxury of a full time coach, and in any event this can be tedious for the coach (or friend/family member).
An automated system is needed to automatically count laps for a swimmer. Such systems have been proposed such as in U.S. Pat. No. 6,870,466 to Rust et al. Rust teaches a system wherein a sensor is placed in the water at one end of the pool. The swimmer wears a device that can communicate with the sensor when they are in close proximity. Thus each time the swimmer approaches the end of the pool, the worn device comes into proximity with the sensor and a lap is counted.